1. Field of the Invention
The present invention relates, generally, to a vehicle seat, and more specifically to a vehicle seat having an active head restraint system.
2. Description of the Related Art
Conventional vehicle seat designs of the type commonly found in the related art typically include a seatback assembly, a lower seat assembly, recliner mechanism, manual or power adjustment mechanism for adjusting a number of positions of either the seatback or lower seat assemblies, as well as a number of safety features including occupant restraint devices such as seatbelts. The seatback assembly also includes a headrest that is typically mounted at the top or upper end of the seatback.
In the context of vehicle seating design, there is an ongoing effort to improve the safety of the vehicle occupant in the event of a collision. More specifically, there continues to be an ongoing effort to provide safety mechanisms that reduce the chance of injury in the region of the passengers"" neck. In the event of a rearward impact, the occupant is forced against the seat and can experience a very large energy pulse. In such circumstances, the pelvis and lumbar regions of the occupant generally exert more force, initially, on the seatback than do the thoracic or shoulder regions of the occupant. This initial load may cause a separation between the seatback and the thoracic, neck, and head regions of the occupant. Depending on the force of the rear impact, this separation can be quickly and violently closed by a following movement of the upper torso, neck, and head of the passenger toward the seatback in an event commonly known as xe2x80x9cwhiplash.xe2x80x9d Thus, there has been an ongoing effort to address this problem in the context of vehicle seating safety.
In the past, the headrest was a relatively static device that was typically moveable up and down or slightly tiltable, but usually in connection with adjustments made for the comfort of any given occupant of the seat during normal driving conditions. However, in order to address the problems encountered during a rearward collision, dynamic or active headrest mechanisms have been proposed in the related art.
For example, U.S. Pat. No. 5,938,279 issued to Schubring et al. and assigned to the assignee of the present invention discloses a dynamic vehicle head restraint assembly that is designed to reduce the amount of separation between the occupant and the seatback in the event of a rearward collision. The head restraint assembly includes an impact or target plate that is supported by the seatback frame in the general area corresponding to the thoracic or shoulder region of the occupant. The impact plate is pivotally mounted to a linkage that is connected to the headrest. In the event of a rearward collision, the force of the occupant on the target plate actuates the linkage to cause the headrest to move upwardly and forwardly toward the head of the occupant, thereby reducing the amount of separation between the occupant and the seatback.
While the dynamic head restraint systems of the type known in the related art were an improvement over the previously known static headrests, there remains a need in the art to better absorb and dissipate the energy generated by the force acting on the seatback in the event of a rearward collision, especially at the pelvic and lumbar areas, which are generally remote from the headrest.
U.S. Pat. No. 6,565,150, assigned to the assignee of the present invention, discloses a vehicle seat having an active headrest that is designed to address this problem. More specifically, the seat has a pivotal support assembly that is mounted to the seatback frame and is operatively connected to the headrest such that the headrest moves upwardly and toward the occupant in the event of a rearward collision. The pivotal support assembly includes a lower impact target that is located in the pelvic and lumbar regions to dissipate the forces that are first translated to the seatback in this area. The lower target is operatively connected to a reaction plate that is pivotally mounted to the seatback. In turn, the headrest is mounted to the reaction plate.
While the dynamic head restraint systems known in the related art have generally worked for their intended purposes and have improved safety, there remains a need in the art for a vehicle seat having an active head restraint system that better absorbs the energy generated by the force at both the pelvic and lumbar regions as well as the force generated at the thoracic or shoulder regions of the occupant. This is especially true in the case of a smaller or narrower seat. Vehicle seats of this type generally inhibit penetration into the seatback at the shoulder region of the occupant in the event of a rearward collision. Furthermore, and as noted above, penetration at the shoulder area into the seatback occurs only after the initial penetration that occurs at the pelvic and lumbar regions of the occupant.
Over and above the need to deal with forces generated in the event of a rearward collision, there is an ongoing need in the related art for a vehicle seat that can withstand greater impacts and thereby provide better factors of safety for the vehicle occupant in the event, for example, of a side impact.
The present invention overcomes these disadvantages in the related art in a vehicle seat assembly that includes a seatback frame and an active head restraint system operatively supported by the seatback frame. The head restraint system includes a headrest, an upper armature, a lower armature, and a linkage operatively interconnecting the upper and lower armatures. The upper armature is pivotally mounted relative to the seatback so as to be generally aligned with the thoracic area of the occupant of the seat assembly. The headrest is operatively mounted to the upper armature. The lower armature is pivotally mounted to the frame in spaced relationship relative to upper armature so as to be generally aligned with the lumbar and pelvic regions of the occupant of the seat assembly. The lower armature is operative to absorb energy generated by a force exceeding a predetermined level at the pelvic and lumbar regions such that the lower armature acts on the upper armature through the linkage to cause the upper armature and the headrest to pivot upwardly and forwardly to move the headrest toward the head of the occupant of the seat assembly in an initial response to an impact exceeding a predetermined force. In addition, the upper armature is further operative to absorb energy generated by a force exceeding a predetermined level at the thoracic region such that the upper armature and the headrest pivots further upwardly and forwardly following the initial response by the lower armature to an impact that exceeds a predetermined force. In addition, the vehicle seat assembly may further include a side impact protection strut that increases the lateral stiffness of the seat and thereby improves side impact performance.
In this way, the vehicle seat assembly of the present invention provides a head restraint system that is responsive to forces that are first generated and imparted to the seatback in the lumbar and pelvic region of the seat occupant even though these regions are disposed relatively remote from the headrest. In addition, the head restraint system of the present invention also acts to absorb and dissipate the energy generated by the force of the occupant that impinges on the seatback near the thoracic or shoulder region of the occupant and acts to further move the headrest upwardly and toward the head of the occupant thereby reducing the separation that can occur between the occupant and the seatback in the event of a collision. Finally, the vehicle seat assembly of the present invention addresses these specific problems in a system that is efficient, robust, and cost effective.